Minimally-invasive intracardiac ablation is the treatment of choice for various types of arrhythmias. To perform such treatment, the physician typically inserts a catheter through the vascular system into the heart, brings the distal end of the catheter into contact with myocardial tissue in areas of abnormal electrical activity, and then energizes one or more electrodes at or near the distal end in order to create tissue necrosis.
A number of systems for intracardiac ablation therapy are commercially available, such as the CARTO™ system offered by Biosense Webster Inc. (Diamond Bar, Calif.). CARTO tracks the position and operating parameters of the distal end of the catheter and displays this information electronically on a three-dimensional (3D) anatomical map of the heart. CARTO enables the system operator to electronically tag locations that have been ablated on the map and thus to keep track of the progress of the procedure.
U.S. Patent Application Publication 2011/0125150, whose disclosure is incorporated herein by reference, describes a system and method for assessing effective delivery of ablation therapy to a tissue in a body. A 3D anatomical map of the tissue is generated and displayed. An index is generated corresponding to a location and indicating a state of ablation therapy at the location. The index may be derived from factors such as the duration an ablation electrode is present at the location, the amount of energy provided, the degree of electrical coupling between the electrode and the tissue, and temperature. A visual characteristic (e.g., color intensity) of a portion of the anatomical map corresponding to the location is altered responsively to the index.